the only way to make it safer, is put more devices on raid1 for example: disks=6 (was wrong on last email) raid0= 1-2(a) 3-4(b) 5-6(c) raid1= a,b,c or raid1=1-2-3(a) 4-5-6(b) raid0=a,b now you can loose tree disks 2011/1/31 Roberto Spadim <roberto@xxxxxxxxxxxxx>: > rewriting.. > using raid10 or raid01 you will have problems if you lose 2 drives too... > if you lose two raid 1 devices you loose raid 1... > see: > > disks=4 > RAID 1+0 > raid1= 1-2(A) ; 3-4(B); 5-6(C) > raid0= A-B-C > if you lose (A,B or C) your raid0 stop > > RAID 0+1 > raid0= 1-2-3(A) ; 4-5-6(B) > raid1= A-B > if you lose (1,4 OR 1,5 OR 1,6 OR 2,4 OR 2,5 OR 2,6 OR 3,4 OR 4,5 OR > 4,6) your raid0 stop > > using raid1+0 or raid0+1 you can't lose two disks... > > > > 2011/1/31 Roberto Spadim <roberto@xxxxxxxxxxxxx>: >> do you have a faster array using raid0+1 or raid1+0? >> >> 2011/1/31 Roberto Spadim <roberto@xxxxxxxxxxxxx>: >>> hum that's right, >>> but not 'increase' (only if you compare raid0+1 betwen raid1+0) using >>> raid1 and after raid0 have LESS point of fail between raid 0 and after >>> raid 1, since the number of point of fail is proportional to number of >>> raid1 devices. >>> >>> 2011/1/31 Robin Hill <robin@xxxxxxxxxxxxxxx>: >>>> On Mon Jan 31, 2011 at 01:00:13PM -0200, Roberto Spadim wrote: >>>> >>>>> i think make two very big raid 0 >>>>> and after raid1 >>>>> is better >>>>> >>>> Not really - you increase the failure risk doing this. With this setup, >>>> a single drive failure from each RAID0 array will lose you the entire >>>> array. With the reverse (RAID0 over RAID1) then you require both drives >>>> in the RAID1 to fail in order to lose the array. Of course, with a 4 >>>> drive array then the risk is the same (33% with 2 drive failures) but >>>> with a 6 drive array it changes to 60% for RAID1 over RAID0 versus 20% >>>> for RAID0 over RAID1. >>>> >>>> Cheers, >>>> Robin >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> >>> >>> >>> >>> -- >>> Roberto Spadim >>> Spadim Technology / SPAEmpresarial >>> >> >> >> >> -- >> Roberto Spadim >> Spadim Technology / SPAEmpresarial >> > > > > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial > -- Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
